Terminal for electric cables



July 26, 1938. c. L. MARKS TERMINAL FOR ELECTRIC CABLES Filed Aug. 26, 1957 w & a w Q 1 M M Q U x M.

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Inventor Charles L.Ma-r-ks, y V 4w 1 His Attorney.

Patented July 26, 1938 UNITED STATES PATENT OFFICE TERMINAL FOR ELECTRIC CABLES Charles h. Marks, Pittsfield, Mass., assignor to General Electric Company, a corporation at New York Application August 26, 1937, Serial No. 131,051

' 4 Claims. {cine- 253} ductor and insulator have unequal expansionsand contractions for the same change of temperature, the flexible connectors may be and sometimes are subjected to such strains as to injure them.

The object of my invention is the provision of an improved cable'terminal in which the-insulator and the flexible connectors are protected at all times from injurious strains.

For a consideration of what I believe'to .be novel and my invention, attention is directed to the accompanying description and the claims appended thereto. Y

In the accompanying drawing which is iliustrative of my invention, Fig. 1 is a view partly in elevation and partly in section of a cable terminal; Fig. 2'is a sectional view ofthe upper part'of the terminal, and Fig. 3 is a plan view of a split-supporting ring.

' I 4 indicates the lead sheath of a cable which is secured to the lower end of-the metal base part or housing 5 of the terminal as'by means of a wipe soldered joint 6, for example. -The cable. may extend downwardly several feet in'a more or lesss vertical direction depending upon the location or the terminal. Thejupper end of the housing has a flange which is supported from the under side as by parts 8, for example. On

- top of the flange is a flanged metal ring 9 in .55 threaded terminal stud l4 having an enlarged which the lower end of the chambered insulator I0 is supported and sealed. As illustrated, the insulator is made of porcelain with numerous parallel ribs to increase the creepage surface but it may be made of other insulating material. Mounted, on top of the insulator and secured thereto in any suitable way is a cap orcover ll, and between it'and the insulator isa packing l2 to ensure a fluid-tight connection. The chamber l3-of the insulator when the cable is ins'ervice is fllled with suitable insulating liquid, such as degasifled oil for example. Supported .by the cap is a, hollow screw 8roove 25 the conductor and head 23 upwardly from the normal or cold position shown head 55 located on the under side of the cap, said stud being firmly secured in place by the external nut l6. Between the upper surface or the head and the under surface of the cap is a fluid-tight pacmng l1. 0n the upper end of the stud is a pair of nuts l8 for uniting it with a line or other conductor. The outer end of the hollow stud is closed by a screw plug is.

The sheath is removed from that portion of the cable within the insulator. till-indicates the condoctor of the cable and in the present illustration has a hollow core 2i which is filled with de gasified oil at super-atmospheric pressure. Surrounding'the conductor is factory applied insulationlz. The conductor-with the insulation removed from the end thereof is locatedin a socketed head 23 and is united therewith, as by solder for'example. Above the head is an extension 24 which makes a loose telescopic fit in the bore or hollow lower' end of the terminal stud and has-a peripheral groove 25, said groove being of a length to permit of the extension moving upwardly within the bore of the stud when the expansion of the conductor is greater. than that of the insulator. Located in the groove is a split ring 26 which supports a portion of the weight of the conductor when it is in the normal position, as shown. The split ring is held against shouldered nut 21, the threads of which engage corresponding threads on the lower end of the terminal stud. Due to the axial length of the can move due to unequal heating oI-the parts but cannot move downwardly from said position. In order to establish and maintain good electrical connection between the relatively movable parts, one or more flexible connectors 28 are provided of which two are shown in the sectional drawing. Each connector has a head 29 at each end which ends are soldered or otherwisesecured to the terminal stud andto the head 23. The connectors are some what longer than the distance between points of attachment so that at no time. are they under longitudinal strains tending to break them or to injurethe points of connection.

'-In the extension 24 of the socketedhead is a passage 30 communicating 'with the hollow core orchannel of.-the cable and terminating at its upper end in a valve seat that cooperates with .thevalve 3| located at the bottom end of a rod 32 which extends upwardly into the terminal stud. The rod has a screw thread at its lower end which engages internal threads in the extension 24. Be-

tween the valve and seat is a lateral port 33 for establishing communication between the cable core and the chamber 53 of the insulator. By removing the screw plug is at the top of the terminal stud and inserting a suitable tool to engage the rod 32, the valve may be moved to close the valve seat at the upper end of the passage 36 or to open it as shown, after which the plug is replaced. The valve El and lateral port 33 are used during the installation of the terminal. While the chamber of the insulator is being evacuated and filled with insulating fluid, such as degasifled oil, the valve would be closed. After the filling operation is completed, the valve is opened and communication established between the core of the cable and the chamber of I the insulator. The plug it is normally in place as shown.

From the foregoing, it will be seen that any weight or pull of the conductor at normal temperature is sustained by the split ring 26 and associated parts, and for that reason no strains are imposed on the flexible'connectors 28. On the other hand, it will be seen that when the conductor expands at a greater rate than the insulator, it can freely move upwardly and that the only feiie'ct on the flexible connectors will Due to the telescopic relation of the stud and the extension 25 as described, the expansion of the conductor will not subject the insulator through the cap to upward pushing effects which 40 otherwise might result in cracking it. Such an 0 relatively stifi and unyielding and that the porcelain insulator is practically a rigid body securely fastened at its lower end; Stated briefly, my improved construction results in a terminal free of internal injurious strains due to unequal expansion and contraction of the parts and of trouble due to small misalignment of the parts.

What I claimas new and desire tosecure by Letters Patent of the United States, is:

l. A terminal for an'electric cable comprising 60 a chambered insulator, a support for the bottom end thereof, a cap for closingthe top of the insulator, a terminal stud mounted on and extending outwardly through the cap, the stud having a bore at its lower end, a conductor within 5 the insulator extending longitudinally thereof, a

head firmly secured to the conductor having an extension at its upper end located within the bore on the stud in movable telescopic relation therewith, a supporting member secured to the lower end of the terminal stud, a means engaging the head and through which it extends located between the extension on the head and the member for limiting the downward movement of the head and conductor but permitting them to move upwardly due to expansion of the conductor, and a flexible connector secured at one end to the terminal stud and at the other cable.

2. A terminal for an electric cable comprising a chambered insulator, a support for the insu-.

lator located at its bottom end, a cap for the top of the insulator, a terminal stud mounted on and extending through the cap, said stud having a head located under the cap containing a central bore, a cable having its sheath connected in fixed relation to the support of the insulator and its conductor extending longitudinally of the. insulator, a head secured to the conductor, said,

head having an extension with a peripheral groove, a ring located in and engaging a wall of the groove for limiting downward movement of the conductor and its head. but permitting upward unrestrained movement thereof, a means carried by the stud for holding the ring against downward movement, and a flexible connector electrically uniting the stud and the conductor head, the ring and means protecting the flexible connector from undue strains due to a downward movement of the cable.

3. A terminal for an electric cable comprising a chambered insulator, a support'for the insulator located at its bottom end, a cap for the top of the insulator, a terminal stud mounted on and extending through the cap, said stud having an externally threaded head located under the cap containing a, central bore, a cable having its sheath connected to the support of the insulator and its-conductor extending longitudinally of the insulator, a head secured to the conductor, said head having a peripheral groove and being arranged in telescopic relation with the bore of the stud; a split ring located in the.

groove and of less axial length than said groove,

a nut carried by the threaded end of the stud for holding the ring against its lower end, and

a flexible connector secured at its ends to the stud and head for electrically uniting them, the ring and nut serving to protect the connector from undue strains due to a downward movement of the cable.

4. A terminal for an electric cable comprising a chambered insulator, a support for the insulator located at its bottom end, a metal cap for closing the top of the insulator, a terminal stud having an enlarged head located under the cap within the insulatorand also a part extending through the cap, the head having a central bore and a screw threaded lower end, a cable within the insulator extending axially thereof, a head secured to the cable having an extension located CHARLES L. MARKS. 

